Method and apparatus for forming cages for roller bearings



Dec. 7, 1965 PlTNER 3,221,390

METHOD AND APPARATUS FOR FORMING CAGES FOR ROLLER BEARINGS Filed Jan. 21, 1965 T- r '1. A

United States Patent 3,221,390 METHOD AND APPARATUS FOR FORMING CAGES FOR ROLLER BEARINGS Alfred Pitner, Paris, France, assignor of one-half to Nadella S.A., Rneil-Malmaison, France, a French body corporate Filed Ian. 21, 1965, Ser. No. 427,031 Ciaims priority, application France, Feb. 19, 1964, 964,324 6 Claims. (Cl. 29148.4)

The present invention relates to cages or cage segments for roller or needle bearings, a method and an apparatus for forming said cages being produced by blanking and bending flat strip.

One of the problems encountered in the production of such cages concerns the provision of means for retaining the rolling elements inwardly and/or outwardly of the cage. In the case of cages whose radius of curvature is relatively small, the convergence of the flanks of each aperture for the rolling element is often sufiicient to retain the latter inwardly of the cage. Usually, however, it is necessary to provide in the flanks of the apertures circumferential projections for retaining the needles or rollers.

It has already been proposed to form such projections in the vicinity of one of the faces of the flat strip by forming inwardly of the apertures radial projections which are obtained directly in the course of the piercing of the apertures in the strip owing to the fact that when the punches pass through the strip, the material is deformed or upset and fits closely against rounded edges or chamfers formed on the edges of the punch-receiving openings in the die adjacent the flanks of the apertures.

This method is not fully satisfactory since the cutting action of the punch on the material which is upset or urged onto the radiused or chamfered edge gives rise to diificulties and often results in an imperfect projection of metal owing to the acute angle formed between the line of action of the punch and the surface of the chamfered or rounded edge. This projection could finally be in the form of burrs which are created on articles pierced with press tools in a worn condition. The difliculty just mentioned restricts moreover the radial dimension it is possible to give to the projection in the course of the piercing and consequently the circumferential dimension of the rolling element-retaining projection of the aperture.

The object of the present invention is to provide a method for forming retaining projections which is devoid of the aforementioned drawbacks owing to the fact that a die is employed in which cavities are formed in the shape of grooves which communicate with the corresponding punch-receiving openings in the die in the direction perpendicular to the edge of said openings.

The width and depth of said grooves are so chosen, as a function of the thickness and nature of the metal to be pierced, that as the punch passes through the plane on which the strip is supported during the piercing operation and enters the punch-receiving opening in the die, it upsets into the bottom of the grooves a portion of the strip which is thereafter cut or pierced during the downward stroke of the punch as the latter passes through the level of the bottom of the groove.

Owing to the angle of 90 between the bottom of the groove and the line of action of the punch, a clean cut is obtained. Consequently, the depth of the grooves can be relatively large and this permits finally obtaining in the flanks of the apertures projections which have, after flattening, a relatively large circumferential dimension which is necessary for the outer retention of the needles or rollers when the angle of convergence of the aperture flanks "ice is large. An example related to this question is disclosed in the French patent of addition No. 964,323, filed by the applicants on February 19, 1964 and entitled Segmented cage for roller or needle bearings.

Further features and advantages of the invention will be apparent from the ensuing description with reference to the accompanying drawing to which the invention is in no way limited.

In the drawing:

FIG. 1 is a vertical sectional view of a punch and die assembly for piercing apertures in a fiat strip;

FIG. 2 is a plan view of the die shown in FIG. 1;

FIG. 3 is a sectional view taken along line 33 of FIG. 2;

FIG. 4 is a longitudinal sectional view of the cage blank obtained by means of the assembly shown in FIG. 1;

FIG. 5 is a diagrammatic sectional view of the final stage of the formation of the retaining projections, and

FIG. 6 is a longitudinal sectional view of the finished cage.

FIG. 1 shows an aperture-piercing press tool assembly comprising a die A and punches B for piercing a flat strip C adapted to form a blank for a cylindrical cage or cage segment. In order to form the apertures 1 in the cage, the die comprises rectangular-shaped punchreceiving openings 2. Grooves 3 which are perpendicular to the large sides 2a of these openings communicate with the latter. According to the invention, these grooves serve to form on one of the faces of the pierced strip and along the large sides 1a, projections 4 which are perpendicular to the plane of the strip. In a subsequent production stage, the projections 4 of the blank shown in FIG. 4 are upset or urged back into the plane of the corresponding face, for example in accordance with FIG. 5, so as to form in the finished cage circumferential projections 5 (FIG. 6) for retaining the rolling elements disposed in the apertures 1. FIG. 5 shows the action of a forming punch D which co-operates with an anvil E for converting a radial projection into a tangential projection.

Retaining projections 6 can also be provided on the other face of the blank (FIG. 6), for example by forming, by means of tools in the form of centre punches, depressions 7 so that the material is upset or urged inwardly of the apertures, the projections thus formed being, if desired, axially offset relative to the projections 5. Projections 4 could also be provided along the small sides I!) of the apertures for the purpose of exerting a retaining action on the ends of the needles or rollers. In this case, grooves 3' perpendicular to the small sides 2]) of the punch-receiving openings 2 in the die would be provided in the latter.

It will be observed that in the event of wear of the die the grooves 3 can be easily sharpened. It can be seen from FIG. 2which shows two groups of grooves 3 which are in the prolongation of each other in each groupthat the sharpening can be obtained by merely passing over the die top a narrow shaping grinding wheel which is fed radially into the die metal. This is an inexpensive operation.

Although specific embodiments of the invention have been described, many modifications and changes may be made therein without departing from the scope of the invention as defined in the appended claims.

Having now described my invention what I claim as new and desire to secure by Letters Patent is:

1. A method for forming rolling element retaining projections in the sides of apertures in a flat strip adapted to form a cage structure for bearings having rolling elements, said method comprising piercing each rolling element receiving aperture in the strip by means of a punch and a die having a punch-receiving opening, upsetting portions of the material of the strip by the action of the punch as it pierces the aperture, the punch upsetting said portions into grooves provided in the top face of the die and cornmunicating with the wall defining said opening so as to form depending projections in the strip, and thereafter urging the depending projections laterally inwardly of the aperture by means of a forming punch and an anvil, the depending projections being placed against the anvil and the forming punch having rounded edges in the region of said projections.

2. A method as claimed in claim 1, wherein each aperture is elongated and extends transversely of the strip, said grooves communicating with the large sides of the die opening forming the aperture.

3. A method as claimed in claim 1, wherein each aperture is elongated and extends transversely of the strip, said grooves communicating with the small sides of the die opening forming the aperture.

4. A method as claimed in claim 1, wherein a plurality of apertures are formed simultaneously in the strip by a plurality of punches and die openings, said rolling element projections being formed by said grooves which extend over the top face of the die and communicate with and interconnect each die opening.

5. A method for forming rolling element retaining projections in the sides of apertures in a flat strip adapted to form a cage structure for bearings having rolling elements, said method comprising piercing each rolling element receiving aperture in the strip by means of a punch and a die having a punch-receiving opening, upsetting portions of the material of the strip by the action of the punch as it pierces the aperture, the punch upsetting said portions into grooves provided in the top face of the die and communicating with the wall defining said opening so as to form depending projections in the strip, and thereafter urging the depending projections laterally inwardly of the aperture by means of a forming punch and an anvil, the depending projections being placed against the anvil and the forming punch having rounded edges in the region of said projections, said method further comprising forming second rolling element retaining projections on the face of the strip opposed to the face on which the firstrnentioned projections are formed, said second projections being formed by striking the strip in close vicinity to the sides of each aperture by center-punches so as to upset small portions of the strip laterally inwardly of the aperture.

6. A press tool assembly for forming rolling element projections in the sides of apertures in a flat strip adapted to form a cage structure for bearings having rolling elements, said assembly comprising punches and a die having punch-receiving openings, and grooves in the top face of the die which communicate with the walls defining said openings, whereby a portion of the material of the strip are upset into said grooves and form depending projections as the punches pierce said apertures.

References Cited by the Examiner UNITED STATES PATENTS 2,998,635 9/1961 Burrittetal 29 14s.4 3,138,849 6/1964 Ortegren 29 14s.4

WHITMORE A. WILTZ, Primary Examiner.

THOMAS H. EAGER, Examiner. 

1. A METHOD FOR FORMING ROLLING ELEMENT RETAINING PROJECTIONS IN THE SIDES OF APERTURES IN A FLAT STRIP ADAPTED TO FORM A CAGE STRUCTURE FOR BEARINGS HAVING ROLLING ELEMENTS, SAID METHOD COMPRISING PIERCING EACH ROLLING ELEMENT RECEIVING APERTURE IN THE STRIP BY MEANS OF THE PUNCH AND A DIE HAVING A PUNCH-RECEIVING OPENING, UPSETTING PORTIONS OF THE MATERIAL OF THE STRIP BY THE ACTION OF THE PUNCH AS IT PIERCES THE APERTURE, THE PUNCH UPSETTING SAID PORTIONS INTO GROOVES PROVIDED IN THE TOP FACE OF THE DIE AND COMMUNICATING WITH THE WALL DEFINING SAID OPENING TO AS TO FORM DEPENDING PROJECTIONS IN THE STRIP, AND THEREAFTER URGING THE DEPENDING PROJECTIONS LATERALLY INWARDLY OF THE APERTURE BY MEANS OF A FORMING PUNCH AND AN ANVIL, THE DEPENDING PROJECTIONS BEING PLACED AGAINST THE ANVIL AND THE FORMING PUNCH HAVING ROUNDED EDGES IN THE REGION OF SAID PROJECTIONS. 